Basic hematology and Immunohematology tests

For MSC in TID &HIV Medicine students

By: By: Mulugeta Melku(BSC, MSC)Mulugeta Melku(BSC, MSC) UOG, GCMHS, UOG, GCMHS,

School Of Biomed.& Lab. Science,School Of Biomed.& Lab. Science, Department of Hematology and Department of Hematology and

Immunohematology Immunohematology

Objectives At the end of the sessions, u will able

to:

Recognized the need to learn H&IH

Explain the principle, interpretation of basic H&IH tests

Basic Hematology tests

3

Definition of Haematology Greek term

Haima - blood Logos – discourse

Hence Haematology is the science or study of blood It encompasses:

the study of blood cells and coagulation Analyses of concentration, structure and

function of cells in blood and their precursors in the bone marrow

Hematology Introduction

Organization of blood and blood forming organs

What is hematology? Hematology is the study of blood which is

composed of plasma (~55%), and the formed elements which are: The erythrocytes (RBCs)

Contain hemoglobin Function in the transport of O2 and CO2

The Leukocytes (WBCs) and platelets (thrombocytes)

Leukocytes are involved in the body’s defense against the invasion of foreign antigens.

Platelets are involved in hemostasis which forms a barrier to limit blood loss at an injured site.

What is hematology? Hematology is primarily a study of the

formed cellular elements. Alterations in the formed elements in the

blood are usually a result of disease rather than being the primary cause of disease. In fact, variations in the formed elements in the

blood are often the first sign that disease is occurring in the body.

The changes caused by disease may be detected by lab tests that measure deviations of the blood constituents from the normal values.

What is hematology? These lab test may include:

RBC count WBC count Platlet count Hematocrit (packed cell volume) Mean corpuscular volume (MCV) Mean corpuscular hemoglobin concentration (MCHC)

Under normal conditions the production, release, and survival of blood cells is a highly regulated process. Quantitative and/or qualitative hematologic abnormalities may result when there is an imbalance between cell production, release, and/or survival.

What is hematology? Age, sex, and geographic location are involved

in physiologic changes in normal values of the formed cellular elements

Pathologic changes in the values of the formed cellular elements occur with disease or injury.

Normal values for a group are determined by calculating the mean for healthy individuals of the group and reporting the normal range as the mean +/- 2 SD

What is hematology? Hematopoiesis is a term describing the

formation and development of blood cells. Cells of the blood are constantly being lost or

destroyed. Thus, to maintain homeostasis, the system must have the capacity for self renewal. This system involves:

Proliferation of progeny stem cells Differentiation and maturation of the stem cells into the

functional cellular elements. In normal adults, the proliferation, differentiation, and

maturation of the hematopoietic cells (RBCs, WBCs, and platlets) is limited to the bone marrow and the widespread lymphatic system and only mature cells are released into the peripheral blood.

Stages in hemopoietic cell development

What is hematology? Hematopoiesis begins as early as the

nineteenth day after fertilization in the yolk sac of the embryo

Only erythrocytes are made The RBCs contain unique fetal hemoglobins

At about 6 weeks of gestation, yolk sac production of erythrocytes decreases and production of RBCs in the human embryo itself begins.

What is hematology? The fetal liver becomes the chief site of blood cell

production. Erythrocytes are produced The beginnings of leukocyte and thrombocyte production

occurs The spleen, kidney, thymus, and lymph nodes

serve as minor sites of blood cell production. The lymph nodes will continue as an important site

of lymphopoiesis (production of lymphocytes) throughout life

bone marrow becomes the primary site of hematopoiesis at about 6 months of gestation.

When the bone marrow becomes the chief site of hematopoiesis leukocyte and thrombocyte production become more prominent.

Hematopoiesis

What is hematology? Hematopoiesis in the bone marrow is called

medullary hematopoiesis Hematopoiesis in areas other then the bone

marrow is called extramedullary hematopoiesis

Extramedullary hematopoiesis may occur in fetal hematopoietic tissue (liver and spleen) of an adult when the bone marrow cannot meet the physiologic needs of the tissues.

Hematopoietic tissue includes tissues involved in the proliferation, maturation, and destruction of blood cells

What is hematology? The mononuclear phagocytic system (also called

RES) is involved in cellular destruction and it includes:

Circulating blood monocytes Fixed macrophages in the bone marrow, liver,

spleen, and lymph nodes

Free macrophages These cells are involved in:

Engulfing particulate matter Processing of antigens for lymphocyte presentation Removal of damaged or senescent cells

What is hematology? Spleen – contains the largest collection of

lymphocytes and mononuclear phagocytes in the body. The spleen functions in:

Filtering and destruction of senescent (aged) or damaged RBCS – also called culling

Removal of particles (are found in some types of anemia) from RBC membranes – also called pitting – this causes a decrease in the surface to volume ratio of the RBC resulting in spherocytes

Enforcing close contact of blood borne antigens with lymphocytes and phagocytic cells – this is more important in children particularly in protection of the host from infections due to enveloped organisms

What is hematology? Sequestering 1/3 of the platelet mass – in massive

splenomegaly this can lead to peripheral thrombocytopenia (decrease in platelets in the blood)

After a splenectomy (removal of the spleen), RBC inclusions and abnormal RBC shapes are seen. Culling is taken over by the liver which is less effective in performing all of the splenic functions

Hypersplenism (splenomegaly) – in a number of conditions the spleen may become enlarged and through an exaggeration of its normal functions of filtering, and destruction and sequestering, it may cause anemia, leukopenia, thrombocytopenia, or cytopenias.

What is hematology? Primary – no underlying disease has been

identified Secondary – caused by an underlying disorder such

as: Inflammatory diseases Infectious diseases Blood disorders that cause compensatory or

workload hypertrophy of the organ such as: Abnormal blood cells, antibody coated blood cells,

hereditary spherocytosis, idiopathic throbocytopenic purpura (ITP)

The effects of these are relieved by splenectomy

Structure of the spleen

What is hematology? Lymph nodes – the lymphatic system is

composed of lymph nodes and lymphatic vessels that drain into the left and right lymphatic duct. Lymph is formed from blood fluid that escapes into the connective tissue.

Lymph nodes are composed of lymphocytes, macrophages, and a reticular network.

They act as filters to remove foreign particles by phagocytic cells

As antigens pass through the lymph nodes, they come into contact with and stimulate immunocompetent lymphocytes to proliferate and differentiate into effector cells.

What is hematology? The structure of the lymph node consists of :

An inner area called the medulla which contains plasma cells

An outer area called the cortex which contains follicles with B lymphocytes surrounded by T lymphocytes and macrophages

Lymph node structure

What is hematology? Thymus – this organ is well developed at birth

and increases in size until puberty at which time it starts to decrease in size.

It serves as a compartment for the maturation of T lymphocytes into immunocompetent T cells. The hormone thymosin plays a role in this process.

The structure of he thymus consists of: An outer area called the cortex which is densely packed

with small lymphocytes and macrophages An inner area called the medulla which is less cellular

with a few lymphocytes, macrophages, and epithelial cells.

Structure of the thymus

What is hematology?Bone marrow – is located inside spongy bone

In a normal adult, ½ of the bone marrow is hematopoietically active (red marrow) and ½ is inactive, fatty marrow (yellow marrow).

The marrow contains both Erythroid (RBC) and leukocyte (WBC) precursors as well as platlet precursors.

Early in life most of the marrow is red marrow and it gradually decreases with age to the adult level of 50%.

In certain pathologic states the bone marrow can increase its activity to 5-10X its normal rate.

When this happens, the bone marrow is said to be hyperplastic because it replaces the yellow marrow with red marrow.

What is hematology? This occurs in conditions where there is increased

or ineffective hematopoiesis. The degree to which the the bone marrow becomes

hyperplastic is related to the severity and duration of the pathologic state.

Pathologic states that cause this include: Acute blood loss in which there is a temporary

replacement of the yellow marrow Severe chronic anemia – erythropoiesis (RBC

production) may increase to the extent that the marrow starts to erode the bone itself.

Malignant disease – both normal red marrow and fatty marrow may be replaced by proliferating abnormal cells.

What is hematology? The hematopoietic tissue may also

become inactive or hypoplastic. This may be due to:

Chemicals Genetics Myeloproliferative disease that replaces

hematopoietic tissue with fiberous tissue

Structure of bone marrow

What is hematology? Liver – contains phagocytic cells known

as Kupffer cells that act as a filter for damaged or aged cells in a manner similar to, but less efficient than the phagocytic cells in the spleen.

If the bone marrow cannot keep up with the physiologic demand for blood cells, the liver may resume the production of blood cells that it began during fetal life

Summary of blood forming organs

Derivation of blood cells Mature blood cells have a limited life span

and with the exception of lymphocytes, are incapable of self-renewal. Replacement of peripheral hematopoietic cells

is a function of the pluripotential (totipotential) stem cells found in the bone marrow

Pluripotential stem cells can differentiate into all of the distinct cell lines with specific functions and they are able to regenerate themselves.

The pluripotential stem cells provide the cellular reserve for the stem cells that are committed to a specific cell line.

Derivation of blood cells The committed lymphoid stem cells will be involved in

lymphopoiesis to produce lymphocytes The committed myeloid stem cell committed myeloid stem cell can differentiate into

any of the other hematopoietic cells including erythrocytes, neutrophils, eosinophils, basophils, monocytes, macrophages, and platlets.

Hematopoietic cells can be divided into three cellular compartments based on maturity:

Pluripotential stem cell capable of self-renewal and differentiation into all blood cell lines.

Committed proginator stem cells destined to develop into distinct cell lines

Mature cells with specialized functions

Hematopoiesis summary

Hematopoiesis

Hematopoiesis